The need for tire pressure gauges has been apparent since the introduction of the pneumatic tire. Various types of tire pressure gauges have been manufactured which perform with varying degrees of accuracy. The most accurate are those using a pressure transducer to measure the air pressure and relay the signal to a display.
Regardless of the method of measuring tire air pressure, the previously mentioned tire gauges all require removal from the tire stem in order to release air from the tire or add air to the tire.
It is also known that some high pressure air hoses are included with a tire gauge so that the pressure can be determined without removing the air hose from the valve stem. However, removal of the air hose from the tire valve stem is still required to release air from the tire, and the air hose must be reapplied to the valve stem in order to read the remaining pressure int he tire after release of an undeterminable amount of air pressure.
Those skilled in the art will appreciate that there is a need for a tire pressure gauge and inflation/deflation device which allows both inflation and deflation of the tire without removal of the tire pressure gauge from the tire valve stem.